This is a multicenter, epidemiological two-part study looking at the prevalence and clinical course of non-tuberculous mycobacteria (NTM) in patients with cystic fibrosis (CF). The purpose of this study is to determine the prevalence of NTM colonization in patients with CF, and to further determine the impact of NTM on the natural course of CF lung disease in US CF Centers. Data generated from the UWMC will contribute to data from approximately 20 study sites nationwide.